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I have been chasing this issue for a while now. It started with transmission failure safty program light, and a 4x4 light when I started the truck on cold mornings (45 degrees or less) So I replaced the battery with a new 720 CCA battery from BMW dealer. Truck worked fine for about a year on the the second year with the new battery same proble came up. So I bought a Bently Service Manual and start chasing this issue. I checked the alternator with a voltmeter at the battery terminals with the engine running at idol and got an accpetable reading according to the manual. Also the alternator was charging fine at least in the warming weather. By the way this never happens in the Spring Summer and early to mid fall. After checking the alternator and checking the battery which were both good, I decided to get a mega-tron 900CCA (cold cranking amps) 1000 AMPs 1000 cranking amps battery. Did so the problem, with during cold starts but not only do I get the transmission failure safty program light, and a 4x4 light but also the ABS and Brake light come on. So I diconnected the negative battery post overnight in hope to reset the ECM. Still no luck same issue happened during a short test drive (1/2 mile run) Then as I am going to work i just so happen to use the orginal key that came with the vechile and no lights, NOTHING! at all works fine.

So I plan to use the old key for a week or two and see what happens. But my questions is could it be that the New Key Fob has stored fault codes and can't release them and or could it be that the Old Key Fob can't remember fault codes? I reflect back to times taking my 335i into the dealership for warranty service and they could read information just from the key and I think the 2004 X5 E53 has this capability as well.

Go to an indy with the proper equipment and have the vehicle scanned for fault codes to see what is causing the idiot lights to display. Then start troubleshooting when you have full information as to where to start and what may be causing the problem.

Well I was proven wrong about the different key fobs, I drove about 40 miles with the old key and the 4X4 light, brake light, and abs light all came on and stayed on for the entire trip. However when I finished purchasing tires (about 30-45 mins of down time) I started the truck and headed home using the same key and no light at all. This morning outside temperture was 50 degress (and the car isn't garage kept) at start up no lights, after about 3 miles of driving the 4X4 light, brake light, and abs light all came on in addition to the Transmission Failure Safety Program message in the dashboard.

Since this use to be only associated with cold weather and the 720CCA battery but now with a 900CCA battery and weather is consistedly cold, I think there is an electrical problem. I do recall that this seem to start happening after GEICO sent my truck to a VW dealer for repairs after an accident. They replace headlights and Parking Distance Sensors but problems only started after 4 to 7 months from the repair.

I will get the fault codes read and post my findings, and thoughts comments etc are welcomed.